Bolt actions - Why did cock-on-opening become the standard?

I would say it mostly about effort. With cock on close you are "direct-drive" with a one to one mechanical relationship to the striker spring and the force required on the bolt handle. With a cock on open you have more mechanical advantage to cock that striker. You get the length of travel the bolt handle over the angular distance it moves during unlock and in most cases that is significantly greater length of motion giving you a lower force over a longer distance to cock the rifle.

Cock on close is alive and well. The modern actions feature straight-pull bolts.

I never paid attention to when my bolts cock. I always thought they cocked when you close the bolt.

CoalCrackerAl said:

I never paid attention to when my bolts cock. I always thought they cocked when you close the bolt.

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Most modern bolt guns cock the firing pin spring when lifting the bolt handle.



Dosent cover the mechanical difference, but does a decent job of covering the operational difference.

I personally dont care for cock on close actions. Ive almost exclusively used cock on open, and the few cock on close, or partial cock on close, Ive used have felt wierd to me.
I could love everything about a gun, but if it were cock on close I don't think id buy it.

Manufacturers made their choice long ago, as said above. Cock on closing is easier to make, but not a big deal for a factory that is tooled up to do cock on opening. All my Mausers are small ring and cock on closing. I once took three shots at a running deer (I did get it) and don't remember a thing about working the bolt.

I once converted a Carcano to cock on opening. But the rifle action I made from scratch is cock on closing.

what I dont like about cock on closing is if you have a round that takes more effort to chamber it is hard to feel it. it is easy to feel with cock on open action

Robin is correct. It does make me careful to get my COAL correct.

Pretty simple - for almost all practical applications, cock on close simply sucks.

As a modern-market example, Seekins originally designed their Havak action as a cock-on-close action. They’ve since been forced by market pressure to redesign the action to conventional cock-on-open, and have offered FREE retrofit conversions of all of their rifles sold with the original design.

What that meant for me: shooting in competition, I would open the action with little resistance while recovering in recoil, but then as I found target again, I’d be forced to push my rifle slightly off target while closing the action to overcome cocking the mainspring. This extra resistance upon close also means it’s more difficult to feel shoulder crush or bullet jam - the bolt handle is dumb. With a cock-on-open design, we get far better tactile feel on our bolt for chambering and less disturbance in the sight picture when closing the bolt on target than we get with a cock-on-close. No upside to cock-on-close to the shooter.

Interesting perspective on the SMLE. Includes a bit on the advantages of cock on closing. Recall that the bolt guns we use today are descendants of the battle rifles developed in the late 19th century. Also, recall that mass fire from bolt guns was used in lieu of machine guns in many cases. I feel that after opening the bolt, the spring gives a "power assist" to the extraction and speeds things up a bit. See



I think that a major reason that there are more cock on opening rifles is that the Mauser and Springfield 03 are cock on opening and that many actions for sporting rifles are just variations on that theme.

Dr T said:

I feel that after opening the bolt, the spring gives a "power assist" to the extraction and speeds things up a bit.

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This only really happens when the bolt is opened WITHOUT having fired the rifle. Yes, the striker spring helps open the bolt on a cock on close action, but really only when the striker spring is under tension - aka, has not been fired.

I don't know if its ever been a major problem, but I do appreciate that the risk of out of battery firing is nearly non existent on a cock on open rifle. Unlikely but far more likely on a cock on close. I believe Peter Mauser lost an eye to an out of battery incident, though on a completely unrelated set of circumstances, it may have been on his mind when he made some of the most influential rifles in history with cock on open.
Of course I have never heard an account of such a thing. I have seen auto loaders slam fire though, and if a bolt rifle slam fires its much more catastrophic.

^this seems backwards to me, functionally.

A cock-on-open action has more opportunity for the compressed striker spring to slip and cause firing as the round is chambered than does a cock-on-close action which can only “follow” as fast as the shooter can close the bolt, which isn’t typically fast enough to fire the round (in my direct experience with a trigger following in my Havak a few years ago, versus following on cock on open R700’s, (non-accutrigger) Savages, and R700 clones).

The cocking piece of striker has to break in a cock on open action to allow the pin to be forward to cause a slamfire - so I don’t believe any plausibility for a forward pin and a true OOBD in a cock on open, whereas cock on open DOES have more energy on the pin spring when closing than a cock on close, so following is far more likely to fire unintentionally in a Coo than in a COC.

jdsingleshot said:

Manufacturers made their choice long ago, as said above. Cock on closing is easier to make, but not a big deal for a factory that is tooled up to do cock on opening. All my Mausers are small ring and cock on closing. I once took three shots at a running deer (I did get it) and don't remember a thing about working the bolt.

I once converted a Carcano to cock on opening. But the rifle action I made from scratch is cock on closing.

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jdsingleshot said:

Manufacturers made their choice long ago, as said above. Cock on closing is easier to make, but not a big deal for a factory that is tooled up to do cock on opening. All my Mausers are small ring and cock on closing. I once took three shots at a running deer (I did get it) and don't remember a thing about working the bolt.

I once converted a Carcano to cock on opening. But the rifle action I made from scratch is cock on closing.

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I have a Carcano that cocks on opening and I don't think it's been converted.

For a military rifle, it was six of one, half dozen of another. The oldest reason I can remember reading was that cock on closing was there to reduce the extraction effort when the rifle got hot, and the ammunition was hot, leading to sticking extraction. I don't know if that is the real reason, or a made up reason. The M1917 Enfield mechanism half cocks the striker on opening. Closing provides the final effort to pull the firing pin back on cam down.

All my small ring mausers are cock on closing



1891 Argentine, cock on closing



Even on a cock on closing mechanism, the firing pin is retracted enough to free the firing pin tip from the primer.




You will find firing pin retraction cams are essential in all rotary bolt designs. Manufacturing tolerances then and now always allowed a certain amount of firing pin off set. Given a bolt that rotates in a circle, the firing pin tip can be broken if the primer indent hole is a little off center. So, the firing pin is always cammed enough to pull the firing pin behind the bolt face.

you see a firing pin retraction cam by turning a M1 carbine receiver up side down



The firing pin is pulled back on a K31 Schmidt Rubin before the lugs rotate






My theory on why cock on closing is not found on commercial rifles has to do with over ride triggers.

The pre 64 M70 has one of the best, and is the earliest over ride trigger I know of, but surely, there are others even earlier.



This is a Timney trigger



These over ride triggers are like trap door mechanisms. You kick away the prop, and the door falls. Notice on the Timney mechanism just how little sear surface engagement there is holding everything together. While I got used to two stage military triggers, and prefer two stage triggers on my target rifles, most shooters hate having an initial take up. So the single stage over ride trigger was developed. You can get a fine and light trigger pull if everything is set up just right. One of the things that will cause an over ridge trigger to "follow" is the bolt cocking piece hitting the trigger sear too hard. A hard hit on the sear will over ride the mechanism and cause the sear to drop.

Used to see that all the time on bolt gunners who adjusted their triggers very light. Oh it worked great in slow fire when the bolt was eased down, but in rapid fire, where the bolt is a flying, a minimum trigger pull weight would result in an alibi. The shooter would be racking that bolt fast, the cocking piece would hit that sear hard, the sear then tripped, the firing pin would go forward, and then the shooter wondering why his gun no go bang.When it happened to me, I always found a slight indentation on the primer, and always wondered why the primer did not go off. And was scared by that indentation.

A cock on closing mechanism would beat the heck out of the typical over ride trigger mechanism. And, you will probably bruise your hand on your scope bell closing the thing. You have to push, remember?

I had the bolt handle lengthened on this M1917, because the handle that Joe Donahue had installed, (he was the first owner) caused my hand to hit the scope bell. And that hurt.

Varminterror said:

.......... With a cock-on-open design, we get far better tactile feel on our bolt for chambering and less disturbance in the sight picture when closing the bolt on target than we get with a cock-on-close. No upside to cock-on-close to the shooter.

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Would you say this detracts from an action like the Blaser R8? I've never used one, and I wouldn't know.

I find cock on close actions annoying because when you lift the bolt without firing it the bolt will sort of pop open on its own. If I was more accustomed to cock on close actions rather than them being the odd one out, I probably wouldn’t mind it. On a rifle that doesn’t lock the bolt shut with the safety this is annoying because it’s really easy to bump the bolt open by accident. A cock on open gun cams the striker back a bit at the top of the bolt travel even when the striker is cocked, so there is a bit of extra resistance that help prevent the bolt from being bumped open accidentally. And even if it is opened accidentally a cock on opening bolt doesn’t fly open on it own like a cock on closing does. A minor annoyance, but a real one that I have experienced.

someguy2800 said:

I find cock on close actions annoying because when you lift the bolt without firing it the bolt will sort of pop open on its own.

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This must be avoidable in some manner of design - I don’t know exactly what Seekins did in particular, but it never felt as if it popped open when cocked/not fired with the old bolt design. Alternatively, if I even LOOK at my B-mag wrong, it springs open like a can of novelty snakes. What I THINK allowed this: the last several degrees of the bolt close felt “flat,” so there was quite a bit of snag and pull to be had before it would actually open.

I do also think even if cock-on-close were the norm, almost any shooter getting a little time behind a cock-on-open rifle would feel the advantages, so it’s more than a matter of “what we’re used to shooting.” A shooter familiar with cock-on-close actions would likely feel as if they were closing on an empty chamber (missed picking up a round) because of the reduced closing stimulus. Side by side, one feels like you’re crush fitting oversized brass on every close.

westernrover said:

Would you say this detracts from an action like the Blaser R8? I've never used one, and I wouldn't know.

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I think folks buying an R8 aren’t typically concerned with most of the same objective analysis which most shooters are considering when they weigh the attributes of different actions. I’m actually not sure how the R8 actually cocks its striker - it’s touted as “manual cocking,” but this only applies to the rear-end manual compression system; I’m not certain when the striker is cocked when firing repeat shots (or any time the action is not starting from the decocked state). Watching videos of the bolt throw, I’d guess it’s actually cock on open.

There is also a good bit of "pay me now or pay me later."
It is the fashion in London Best shops to provide for "easy opening" of top of the line double shotguns and express rifles.
As one wag put it, all that gets you is "hard closing."

Here is the Savage Impulse action:

Varminterror said:

I do also think even if cock-on-close were the norm, almost any shooter getting a little time behind a cock-on-open rifle would feel the advantages, so it’s more than a matter of “what we’re used to shooting.” A shooter familiar with cock-on-close actions would likely feel as if they were closing on an empty chamber (missed picking up a round) because of the reduced closing stimulus. Side by side, one feels like you’re crush fitting oversized brass on every close.

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Would probably also feel like you had sticky extraction due to caming the striker on opening

jdsingleshot said:

But the rifle action I made from scratch is cock on closing.

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I've made a few guns from scratch myself. We would love to see a few pics!

There's not that much difference, beyond personal preference and experience. And those latter two do matter.

The one theory suggests that the shooter is applying more effort on the Open, than on the close, so the additional effort is negligible.
Also that "breaking" your grip on the Open is not that big an issue as on Close, when one wants to be "set" and developing one's aim.
There is a notion, among the academic, that there is some safety in locking back the firing pin on Open.

Against all that is the wide array of successful, safe and use-able rifles that cock on Close.

It's not something I'd base a purchase decision upon.

First, in response to "Of course I have never heard an account of such a thing. I have seen auto loaders slam fire though, and if a bolt rifle slam fires its much more catastrophic." All the bolt action centerfires that I know of have the rear of the bolt where it cams the cocking piece (or doesn't with cock-on-closing) shaped such that the firing pin cannot reach the bolt face unless the bolt is closed. I made my scratch-built with that feature too.